#include<stdio.h>
#include<windows.h>

int main()
{
	int score,n;
	scanf("%d",&score);
	n=score/10;
	switch(n)
	{
		case 6:printf("D\n");	break;
		case 7:printf("C\n");	break;
		case 8:printf("B\n");	break;
		case 9:printf("A\n");	break;
		case 10:printf("A\n"); break;
		default: printf("E\n"); break;
	}
	system("pause");
	return 0;
} 
